Devices and methods for strengthening the thenar muscles

ABSTRACT

Described here are devices and methods for strengthening the thenar muscles of the hand. Generally, a device comprises a base shaped to be held in the hand, a thumb rest having a hinge attached to the base such that one end of the thumb rest can be pivoted relative to the base, and an elastic member attached to the base and the thumb rest, which resists the pivoting motion of the thumb rest relative to the base. The user can place the device in his or her hand, and place his or her thumb on the thumb rest. When the user presses the thumb rest toward the base with his or her thumb, the elastic member supplies a force resisting the pressing motion, which exercises the thenar muscles.

PRIORITY

This application claims priority to U.S. Provisional Application No.61/763,944 filed on Feb. 12, 2013, the entire contents of which areincorporated herein by reference.

FIELD

This relates to a device for strengthening the thenar muscles in thehand.

BACKGROUND

Manual dexterity and strength are important for performing activities ofdaily living but often decline with age. In particular, age isassociated with decreased ability to perform gripping actions, which areneeded for many daily tasks, such as opening jars and bottles. Grippingactions are dependent on the muscular power of the thenar muscles in thepalm of the hand, which include the abductor pollicis brevis, flexorpollicis brevis, and opponens pollicis. These muscles are located at thebase of the thumb and abduct, flex, and oppose the thumb. Their strengthhas been shown to decrease significantly with age, with healthy subjectsbetween 60 and 90 years old having on average half of the motor units intheir thenar muscles as compared to subjects between 20 and 40 years old(T J Doherty & W F Brown, “The estimated numbers and relative sizes ofthenar motor units as selected by multiple point stimulation in youngand older adults,” Muscle Nerve 16(4): 355-66 (1993)). Gripping ability,and in turn the ability to perform daily activities, can thus beimproved by strengthening the thenar muscles of the hand.

While there are some products that can be used to strengthen the musclesof the hand generally—for example, Theraputty™, a malleable, dough-likeputty that can be squeezed—they do not ensure that the user performs thespecific motion that will isolate the thenar muscles. Thus, there is aneed for a device that guides the user to perform an exercisespecifically targeting the thenar muscles for strengthening.

SUMMARY OF THE INVENTION

Described here are devices and methods for strengthening the thenarmuscles of the hand. Generally, the devices comprise a base shaped to beheld in the hand, a thumb rest having a hinge attached to the base, suchthat one end of the thumb rest can be pivoted relative to the base, andan elastic member, such as a spring, attached to the base and the thumbrest, resisting the pivoting motion of the thumb rest toward the base.The user can place the device in his or her hand and place his or herthumb on the thumb rest. When the user presses the thumb rest toward thebase with his or her thumb, the elastic member supplies a forceresisting the pressing motion. The thumb rest is positioned such thatthe thumb is pressed toward the pinky finger, which specifically targetsthe thenar muscles.

The devices provide several advantages. They may guide the user toperform a specific motion with the thumb that isolates the thenarmuscles, specifically targeting them for strengthening. Moreover, thedevices may be not only deformable but may also return to their originalshape after each complete motion of the thumb, allowing the exercise tobe easily repeated. The devices may also be portable and manufactured ata low cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary device for strengthening the thenarmuscles.

FIG. 2 illustrates an exemplary thumb rest.

FIG. 3 illustrates another exemplary thumb rest having a splint-likedesign.

FIG. 4A illustrates an exemplary elastic element comprising acompression spring attached to the thumb rest of FIG. 2.

FIG. 4B illustrates an exemplary elastic element comprising acompression spring within a compressible casing attached to the thumbrest of FIG. 2, with the compressible casing shown in a cross-sectionalview.

FIGS. 5A and 5B illustrate exemplary elastic elements comprisingpiston-like designs attached to the thumb rest of FIG. 2, with theelastic elements shown in cross-sectional views.

FIGS. 6A, 6B, and 6C illustrate exemplary perspective, top, and sideviews of a base, respectively.

FIG. 7 illustrates an exemplary base with an attached strap.

FIG. 8 illustrates an exemplary method for using the device tostrengthen the thenar muscles.

DETAILED DESCRIPTION

In the following description of preferred embodiments, reference is madeto the accompanying drawings in which illustration of specificembodiments of the invention are shown. It should be understood thatother embodiments can be used and structural changes can be made withoutdeparting from the scope of the invention.

This relates to a device for strengthening the thenar muscles of thehand. Generally, the device may comprise a base, a thumb rest attachedto the base, and an elastic element that may be attached directly orindirectly at one end to the base and at the other end to the thumbrest. The device may be configured such that when the device is held inthe hand and the thumb is placed on the thumb rest, pressing the thumbdown to deform the elastic element causes the thenar muscles tocontract. Repeating this motion with the thumb can lead to increasedthenar muscle strength.

A particular embodiment of the invention is a device for strengtheningthe thenar muscles of the hand comprising a base, wherein the base isshaped to fit in the hand, a thumb rest attached to the base, and anelastic member comprising a first end and a second end, wherein thefirst end is attached to the base and the second end is attached to thethumb rest, and wherein the elastic member is configured to deform whenthe thumb rest is pressed. The thumb rest may comprise a hinge and/or aretention member configured to keep the thumb in place while the thumbrest is pressed. The elastic member may comprise a compression spring, apiston, and/or an extension spring. The first end of the elastic membermay be indirectly attached to the base. The base may comprise a concaveside configured to fit against the fleshy part of the palm of the handnear the thumb of the hand, and/or a texturized surface. The base maycomprise a strap that fits around the hand. The device may be configuredto strengthen the thenar muscles of both the left and right hands.

A particular embodiment of the invention is a handheld device forexercising the thenar muscles of the hand comprising a first rigidobject, a second rigid object, a hinge directly or indirectly connectingthe first rigid object and the second rigid object, wherein the hinge isconfigured to cause the first rigid object to pivot relative to thesecond rigid object, and an elastic member, wherein the elastic memberis attached to both the first and the second rigid objects, and whereinthe elastic member is configured to resist the pivoting of the firstrigid object toward the second rigid object. The first rigid object maybe configured to be pivoted toward the second rigid object by pressingthe thumb of the hand against the first rigid object and towards thepalm of the hand. The device may be configured to activate the thenarmuscles when the first rigid object is pressed by the thumb towards thepalm. The device may further comprise a base configured to be held inthe hand, wherein the hinge directly connects the first rigid object andthe second rigid object, and wherein the second rigid object is attachedto the base. The elastic member may comprise a compression spring and/oran extension spring.

A particular embodiment of the invention is a method for strengtheningthe thenar muscles of the hand using a handheld device, wherein thehandheld device comprises a base, a thumb rest attached to the base, andan elastic member having a first end and a second end, and wherein thefirst end is attached to the base and the second end is attached to thethumb rest. The method may comprise pressing the thumb rest toward thebase to deform the elastic member using the thumb of the hand, whereinpressing the thumb rest causes the thenar muscles of the hand tocontract.

The devices provide several advantages. They may guide the user toperform a specific motion with the thumb that isolates the thenarmuscles, specifically targeting them for strengthening. Moreover, theymay be not only deformable but may also return to their original shapeafter each complete motion of the thumb, allowing the exercise to beeasily repeated. The devices may also be portable and manufactured at alow cost.

As used herein, “elastic” or “elasticity” describes a property of amaterial that returns to its original shape after being deformed.

FIG. 1 illustrates an exemplary device for strengthening the thenarmuscles of the hand. In the example of FIG. 1, the device 100 mayinclude a base 102, thumb rest 104, and compression spring 106. Base 102may have a flat shape with three straight sides 124, 126, and 128, oneconvex side 130, and one concave side 132. Base 102 may be shaped to becomfortably held in the left hand, such that the fleshy part of the palmlocated near the thumb can fit against the concave side 132 of the base102, and the fingers of the left hand can be curled around convex side130, but need not be.

As shown in FIG. 1, the thumb rest 104 may comprise two members 108 and110 connected by a hinge 112. Lower member 108 of thumb rest 104 may beattached to base 102 along the concave side 132, where the user's thumbcan rest on the thumb rest when the device is held in the left palm. Theposition of thumb rest 104 may be such that pushing down on it with thethumb while holding the base causes the thumb to make an opposing motiontoward the first knuckle of the pinky finger, which isolates the thenarmuscles. Lower member 108 may be attached to base 102 by any suitablemechanism, such as but not limited to a hook-and-loop fastener, such asVelcro™, screws, adhesive, or the like. Upper member 110 may remain freeto pivot around hinge 112, moving its distal end 116 toward and awayfrom base 102. Attached to distal end 116 of upper member 110 may be thefirst end 120 of the compression spring 106. The second end 122 ofcompression spring 106 may be connected to lower member 108 of thumbrest 104, which may be in turn attached to base 102. Thus, the secondend 122 of compression spring 106 may be indirectly attached to base102. Alternatively, the second end 122 of compression spring 106 may bedirectly attached to base 102. The ends 120, 122 of the compressionspring 106 can be either permanently or detachably fixed to the thumbrest 104 and/or the base 102. The configuration of the base 102 andthumb rest 104 may be altered for use with the right hand, as will bedescribed in more detail below.

When base 102 is held in the left hand, the thumb can be placed on theupper member 110 of thumb rest 104. When the thumb is pressed downwardtoward the pinky finger of the hand, the upper member 110 of thumb rest104 may be pushed downward toward lower member 108 and toward base 102,pivoting around hinge 112. As a result, compression spring 106 may becompressed, creating a force resisting the motion of the thumb towardthe pinky finger. This motion of the thumb may cause the thenar musclesof the hand to contract. When the thumb is released, the stored energyin compressed compression spring 106 may cause upper member 110 of thumbrest 104 to pivot around hinge 112 and move away from lower member 108and away from base 102, returning to its original position. Each elementof device 100 will be described in greater detail below.

FIG. 2 illustrates the exemplary thumb rest of the embodiment of device100 in FIG. 1. As described above, the thumb rest 200 may have a bottommember 202 and a top member 204, connected by a hinge 206. The bottom202 and top 204 members may be made of any material or materials rigidenough not to deform when the device is used, such as but not limited tometal, plastic, or rubber. The bottom 202 and top 204 members may beshaped as tapered rectangles, with rounded ends 212 and 214,respectively. The tapered rectangles may be dimensioned such that auser's thumb can fit comfortably on top member 204, and the distal endof the thumb is near end 214. In one variation, the width of the bottommember 202 at end 208 and the width of top member 204 at end 210, nearhinge 206, may be about 1⅛ inches. The width of bottom member 202 at end212 and top member 204 at end 214 may be about 7/16 inches. The lengthof bottom 202 and top 204 members may be about 2 inches. In othervariations, the thumb rest may have different dimensions to accommodatethumbs of different sizes. In some variations, the width of bottommember 202 at end 208 and top member 204 at end 210 may be about ½inches to about 3 inches; the width of bottom member 202 at end 212 andtop member 204 at end 214 may be about 1/32 inches to about 3 inches.The length of bottom 202 and top 204 members may be about 1 inches toabout 5 inches. In yet other variations, the top member 204 may have anadjustable length, allowing it to be lengthened or shortened to matchthe thumb of the user. For example, top member 204 may comprise twoslidably connected members, where sliding them apart lengthens topmember 204, and sliding them together shortens top member 204. In such avariation, top member 204 may comprise a locking mechanism to maintain aselected length during use. It should be understood that the specificmeasurements of the thumb rest described herein are for explanatorypurposes and do not limit the thumb rest thereto. It should beunderstood that the bottom 202 and top 204 members of thumb rest 200 mayhave different dimensions from each other.

It should also be appreciated that in other variations the bottom 202and top 204 members of thumb rest 200 may have other shapes, and neednot have the same shape as each other. For example, top member 204 mayhave any shape suitable for the user's thumb to apply pressure, such asbut not limited to a rectangle, an oval, or triangle. In somevariations, the top member 204 may have a concave shape so that thethumb can rest more easily on it. In some variations, top member 204 maybe made of more than one separate element. Bottom member 202 may haveany shape suitable for connecting the thumb rest 204 to the base. Insome variations, the bottom member 202 and/or top member 204 may haveholes, hooks, or other elements for attaching the elastic member ofdevice 100 to ends 212 and 214, as will be described in more detailbelow.

Hinge 206 may be located at end 208 of bottom member 202 and end 210 oftop member 204, such that ends 208 of bottom member 202 and 210 of topmember 204 remain fixed, while hinge 206 may allow end 212 and end 214to move toward and away from each other. Bottom member 202 may have acentral tab 216 extending from end 208 that wraps around a pin 218. Topmember 204 may have two outer tabs 220 and 222 extending from end 210that wrap around pin 218 on either side of central tab 216. Central tab216 and outer tabs 220 and 222 may be pivotable about pin 218, creatinghinge 206. It should be appreciated that a hinge may be created throughother mechanisms. For example, thumb rest 200 may not have a bottommember 202, and hinge 206 may be directly attached to the base of device100. As another example, hinge 206 may be integral to the base. Itshould also be appreciated that other elements can comprise the hinge,such as but not limited to a ball and socket, a spring, a deformableelbow joint, a hook, or the like.

FIG. 3 illustrates another exemplary thumb rest 300 having a splint-likedesign with padding and retention members to hold the thumb in place. Asin the example of FIGS. 1 and 2, the thumb rest 300 of FIG. 3 may have abottom member 302 and a top member 304, connected by a hinge 306. Thebottom 302 and top 304 members may be shaped as tapered rectangles andcomprise rigid layers 316 and 318, respectively. The rigid layers 316and 318 may comprise any material rigid enough not to deform when thedevice is used, such as but not limited to a metal, plastic, or rubber.The bottom 302 and top 304 members of thumb rest 300 may have similardimensions to those described above with respect to thumb rest 200 ofFIG. 2. In some variations, the bottom 302 and top 304 members of thumbrest 300 may have similar variations in shape and dimensions as thosedescribed above with respect to thumb rest 200 of FIG. 2. Likewise, thebottom 302 and top 304 members of thumb rest 300 may have elements forattaching the elastic member, as described above with respect to thumbrest 200 of FIG. 2 and described in more detail below. Hinge 306 mayhave a similar design to hinge 206 of FIG. 2, as described in detailabove. Generally, hinge 306 may be located at end 308 of rigid layer 316and end 310 of rigid layer 318, such that end 308 and end 310 remainfixed, while hinge 306 may allow end 312 of rigid layer 316 and end 314of rigid layer 318 to move toward and away from each other. Hinge 306may be formed by tabs extending from end 308 and end 310 that can pivotabout pin 307, in the same manner as hinge 206 of FIG. 2, as discussedin more detail above. Similarly, the hinge may be created through othermechanisms, as described in more detail above with respect to hinge 206of FIG. 2.

In the example of FIG. 3, top member 304 may comprise additionalelements to make the thumb rest more comfortable for the user and tokeep the user's thumb in place during use. For example, above rigidlayer 318 of top member 304 may be a padding layer 320. The paddinglayer 320 may be made of any material or materials capable of conformingto or cushioning the thumb to make the thumb rest 300 more comfortable,such as but not limited to polyurethane foam, rubber, or silicone. Thepadding layer 320 may be concave to allow the thumb to rest easily onthumb rest 300. Although not shown in FIG. 3, in some variations, rigidlayer 318 may also be concave. The padding layer 320 may be glued orotherwise attached to rigid layer 318. In addition, extending from thelong sides 322 and 324 of top member 304 may be four retention memberscomprising retention tabs 326 and 328 (located on long side 322) and 330and 332 (located on long side 324). Retention tabs 326, 328, 330, and332 may help to hold the thumb in place while the thumb is pressed downon thumb rest 300. Retention tabs 326, 328, 330, and 332 may compriseouter rigid layers 334 and inner padding layers 336. The outer rigidlayers 334 may be made of any material sufficiently rigid to hold thethumb in place, such as but not limited to a metal, plastic, or rubber.The outer rigid layers 334 of retention tabs 326, 328, 330, and 332 maybe integral to rigid layer 318 of top member 304, or they may beseparate pieces attached to rigid layer 318. The inner padding layersmay be made of any material capable of conforming to or cushioning thethumb to make the retention tabs more comfortable for the user, such asbut not limited to polyurethane foam, rubber, or silicone. The paddinglayers 336 of retention tabs 326, 328, 330, and 332 may be integral topadding layer 320 of top member 304, or they may be separate pieces.Padding layers 336 may be glued or otherwise attached to the rigid layer334 of each retention tab.

It should be appreciated that the thumb rest may have other designs tomake the thumb rest more comfortable for the user and/or to keep theuser's thumb in place during use. For example, the thumb rest may havefewer or more retention tabs (e.g., zero, one, two, three, five, six, ormore), and/or the retention members may have a different shape. Forexample, the top member 304 may have one retention member extendingalong the entire long side 322 and another retention member extendingalong the entire long side 324 forming hollow half-cylinder-like shape.As another example, a retention member may extend upwards from the end314 of top member 304 and then curve back parallel to and above topmember 304, forming a U-shape that can fit over the user's thumb, suchthat the thumb is enclosed on its anterior and posterior sides butexposed on its medial and lateral sides. In some variations, thepositions of the retention tabs may be adjustable after manufacturing,for example by using a pair of pliers.

FIG. 4A illustrates the exemplary elastic element of FIG. 1 comprising acompression spring 400 attached to the exemplary thumb rest of FIGS. 1and 2. Compression spring 400 may have a first end 402 and a second end404. The first end 402 may be connected to end 212 of bottom member 202of thumb rest 200, and the second end 404 may be connected to end 214 oftop member 204 of thumb rest 200. In the example of FIG. 4A, end 402 maybe wrapped through a hole 406 in end 212 of bottom member 202, and end404 may be wrapped through a hole 408 in end 214 of top member 204. Theends 402 and 404 may be detachable from the holes 406 and 408, so thatthe compression spring 400 can be removed and/or replaced. In othervariations, ends 402 and 404 of compression spring 400 may be attachedto bottom 202 and top 204 members of thumb rest 200 in any suitablemanner, including but not limited to being welded or held in place by ascrew or hook.

When end 214 of top member 204 is pressed toward end 212 of bottommember 202, compression spring 400 may be compressed. As compressionspring 400 is compressed, it may exert a force resisting thecompression. Thus, when the user's thumb is used to compress thecompression spring 400, the thumb must overcome the resistive force ofthe compression spring 400, which may activate the thenar muscles. Whenpressure on the top member 204 from the thumb is released, thecompression spring 400 may return to its expanded configuration (asshown in FIG. 4A). The magnitude of the resistive force that the thumbmust overcome may be proportional to the stiffness of the compressionspring 400. Thus, the compression spring 400 may be chosen based on thedesired force to be applied by the thumb. In one variation, thecompression spring 400 may have a spring rate of about 20 pounds perinch (i.e., the compression spring 400 may require 20 pounds of pressureto compress by 1 inch). In other variations the compression spring 400may have a spring rate of about 0.1 pounds/inch to about 2 pounds/inch,2 pounds/inch to 5 pounds/inch, about 5 pounds/inch to about 10pounds/inch, about 10 pounds/inch to about 15 pounds/inch, about 15pounds/inch to about 20 pounds/inch, about 20 pounds/inch to about 25pounds/inch, about 25 pounds/inch to about 30 pounds/inch, about 30pounds/inch to about 35 pounds/inch, about 35 pounds/inch to about 40pounds/inch, about 40 pounds/inch to about 45 pounds/inch, about 45pounds/inch to about 50 pounds/inch, about 50 pounds/inch to about 55pounds/inch, or about 55 pounds/inch to about 60 pounds/inch.Compression spring 400 may be made of any suitable material ormaterials, such as but not limited to steel or steel alloys, nickel ornickel alloys, titanium, and/or Elgiloy™. In some variations, thecompression spring 400 may be interchangeable such that the user maychoose which compression spring to attach to the device (e.g., the usermay increase the stiffness of the compression spring as the thenarmuscles are strengthened over time). In these variations, thecompression spring 400 may be attached to the top 204 and bottom 202members of the thumb rest 200 by a mechanism that can be easily releasedand re-attached.

The elastic member may have other designs. For example, FIG. 4Billustrates an alternative exemplary elastic member in which thecompression spring 400 of FIG. 4A is within a compressible casing 450.For purposes of explanation, the compressible casing 450 is shown in across-sectional view. The compressible casing 450 may have a generallycylindrical shape and may fit around compression spring 400 to ensurethat, as compression spring 400 is compressed by pressing on the thumbrest 200, the compression spring 400 does not bend instead ofcompressing. In the example of FIG. 4B, the compressible casing 450 maycomprise an outer cylinder 452 and an inner cylinder 454. Outer cylinder452 may have a closed bottom end 456 and an open top end 458, and innercylinder 454 may have a closed top end 460 and open bottom end 462.Outer cylinder 452 may have a larger diameter than inner cylinder 454.Thus, inner cylinder 454 may fit slidably within outer cylinder 452 toform a piecewise hollow cylinder with closed ends. Compression spring400 may be located within the piecewise hollow cylinder. The compressionspring 400 may be attached at its top and bottom ends to end 460 ofinner cylinder 454 and end 456 of outer cylinder 452, respectively, butneed not be so that the compression spring can be removed and/orreplaced.

Bottom end 456 of outer cylinder 452 may be attached to end 212 ofbottom member 202 of thumb rest 200, and top end 460 of inner cylinder454 may be attached to end 214 of top member 204. As compression spring400 is compressed, inner cylinder 454 may slide within outer cylinder452, shortening the overall length of the piecewise hollow cylinder.When pressure on the top member 204 of thumb rest 200 is released, thecompression spring 400 may return to its expanded configuration, causinginner cylinder 454 to extend from within outer cylinder 452, lengtheningthe overall piecewise hollow cylinder to its expanded configuration (asshown in FIG. 4B). In some variations, the compressible casing 450 mayhave other designs. For example, the inner and outer cylinders may bereversed such that the inner cylinder is attached to bottom member 202and the outer cylinder is attached to top member 204. As anotherexample, the compressible casing 450 may comprise three or morecylinders, forming a telescoping cylinder formation. Such a design mayallow the top member 204 of thumb rest 200 to be pressed closer tobottom member 202, since the minimum length of compressible casing 450may be shorter. In some variations, the cylinders making up compressiblecasing 450 may have lips or other mechanisms to prevent the cylindersfrom disconnecting with each other.

FIG. 5A illustrates another alternative exemplary elastic member 500having a piston-like design. For purposes of explanation, the elasticmember 500 is shown in a cross-sectional view. In the example of FIG.5A, the piston-like elastic member 500 may comprise a spring-biasedpiston 502 within a hollow cylinder 504. Piston 502 may be attached toone end of a piston rod 506, which may extend out of hollow cylinder 504through opening 508 in the top end 510 of hollow cylinder 504. The otherend of piston rod 506 may be attached to end 214 of top member 204 ofthumb rest 200. The bottom end 516 of hollow cylinder 504 may beattached to end 212 of bottom member 202. A compression spring 512 maybe located within hollow cylinder 504 between piston 502 and the bottomend 516 of hollow cylinder 504. When the user presses with his or herthumb downward on the top member 204 of thumb rest 200, piston rod 506and piston 502 may be pushed downward within hollow cylinder 504 towardthe bottom end 516. As piston 502 is pushed downward, compression spring512 may be compressed. The compression spring 512 in turn exerts a forceresisting the compression, which must be overcome by the thumb,activating the thenar muscles. In some variations, piston-like elasticmember 500 may be interchangeable, such that the user may choose apiston-like elastic member 500 having a compression spring with adesired stiffness. In these variations, the piston-like elastic member500 may be attached to the top 204 and bottom 202 members of the thumbrest 200 by a mechanism that may allow it to be easily released andre-attached. In another variation, the compression spring 512 within thepiston-like elastic member 500 may be interchangeable. In anothervariation, the top end 510 and/or the bottom end 516 of the hollowcylinder 504 may be removable to expose the cylinder interior for easyinterchange of the compression spring 512.

FIG. 5B illustrates another alternative exemplary elastic member havinga piston-like design 550, having an extension spring 552 instead of acompression spring. For purposes of explanation, the elastic member 550is shown in a cross-sectional view. In the example of FIG. 5B, anextension spring 552 may be located within hollow cylinder 504 andattached at one end to piston 502 and at the other end to the top end510 of hollow cylinder 504. The attachment may be by any suitablemethod, such as but not limited to hooks or loops. When the user presseswith his or her thumb downward on top member 204 of thumb rest 200,piston rod 506 and piston 502 may be pushed downward, which in turnstretches extension spring 552. As extension spring 552 is stretched, itmay exert a force resisting the extension. Thus, the thumb may need toovercome the resistive force of the extension spring 552, whichactivates the thenar muscles. When pressure on the top member 204 fromthe thumb is released, the extension spring 552 returns to itsunstretched configuration, causing piston 502 to move upward toward end510 of hollow cylinder to its original position.

As with a compression spring, the magnitude of the resistive force thatthe thumb may need to overcome due to extension spring 552 isproportional to the stiffness of the extension spring 552. Thus, theextension spring 552 may be chosen based on the desired force to beapplied by the thumb and may have a similar range of spring rates asdescribed with respect to compression spring 400 of FIGS. 4A-4B and 5A.Extension spring 552 may be made of any suitable material or materials,such as but not limited to steel or steel alloys, nickel or nickelalloys, titanium, and/or Elgiloy™. In some variations, piston-likeelastic member 550 may be interchangeable, such that the user may choosea piston-like elastic member 550 having an extension spring with adesired stiffness. In these variations, the piston-like elastic member550 may be attached to the top 204 and bottom 202 members of the thumbrest 200 by a mechanism such that it can be easily released andre-attached. In another variation, the extension spring 552 within thepiston-like elastic member 550 may be interchangeable. In anothervariation, the top end 510 and/or the bottom end 516 of the hollowcylinder 504 may be removable to expose the cylinder interior for easyinterchange of the extension spring 552.

It should be appreciated that the elastic member may have other designs,including variations and combinations of the elastic members describedabove. For example, in an alternative exemplary piston-like design, theelastic member may be similar to those in FIGS. 5A and 5B but may haveboth a compression spring below piston 502 and an extension spring abovepiston 502. In another alternative embodiment, the elastic member (e.g.,any of those described above) may be attached to top member 204 of thethumb rest 200 at a middle location along the length of top member 204,rather than at end 214. In yet another alternative embodiment, thedevice may comprise two or more elastic members.

FIGS. 6A, 6B, and 6C illustrate exemplary perspective, top, and sideviews, respectively, of the base of the device described here. In theexample of FIGS. 6A-6C, the base 600 may be shaped to be comfortablyheld in the left hand. Base 600 may have seven sides: two parallel sides602 and 604 may form the top flat surface and the bottom flat surface,respectively; two parallel straight sides 606 and 608 may form the leftand right edges, respectively; convex side 610 may form the top edge;straight side 612 may form the bottom edge; and concave side 614 mayform an edge connecting edges 606 and 612. Concave edge 614 may beshaped such that the fleshy part of the left palm located near the thumbfits against it. Convex edge 610 may be shaped to align approximatelywith the first knuckles of the left fingers, such that the fingers ofthe left hand can be comfortably curled around convex edge 610, but neednot be. In the example of FIGS. 6A-6C, straight edge 606 may be about1.13 inches long; straight edge 608 may be about 2.36 inches long;convex edge 610 may be about 3.5 inches across, with a radius ofcurvature of about 4.38 inches; straight edge 612 may be about 1.09inches long; the corner between straight edges 608 and 612 may have aradius of curvature of about 0.25 inches; and concave edge 614 may havea radius of curvature of about 3.50 inches. The thickness of base 600(i.e., the distance between the top flat surface 602 and the bottom flatsurface 604) may be about 0.50 inches. The corners between the top flatsurface 602 and the edges may have a radius of curvature of about 0.13inches, and the corners between the bottom flat surface 604 and theedges may have a radius of curvature of about 0.06 inches. In othervariations, the base may have different dimensions and curvatures toaccommodate hands of different sizes. In some variations, edge 606 maybe about 0.5 to 3 inches long; edge 608 may be about 1 to 6 inches long;edge 610 may be about 1 to 8 inches across, with a radius of curvatureof about 1 to 8 inches; edge 612 may be about 0.2 to 3 inches long; andedge 614 may have a radius of curvature of about 1 to 8 inches. In somevariations, the corners between two edges and between an edge and a flatsurface may be right angles, or they may have a greater radius ofcurvature than in the example of FIGS. 6A-6C. It should be understoodthat the specific measurements of the base described herein are forexplanatory purposes and do not limit the base thereto. It should alsobe understood that the base may have other shapes and different numbersof edges than the ones described here.

The base may be made out of any suitable material or materials, such asbut not limited to a molded plastic, rubber, or metal. In somevariations, the surfaces and/or edges of the base 600 may be texturizedto help the user hold the base more securely. In other variations, allor a portion of the base may be covered with a material or materials,such as but not limited to a fabric, rubber, or silicone, to help theuser hold the base more securely (for example by absorbing sweat orproviding a tacky surface for gripping), to make the base morecomfortable to hold, or to make the appearance of the device morepleasing. In other variations, the base itself or the material coveringthe base may be decorated with logos, patterns, designs, and/or colorsto provide the pleasing appearance.

Although the device described thus far is configured for use in the lefthand, in other variations the device may be configured for use in theright hand, or it may be configured for use in either hand. In onevariation for use in the right hand, the base may be a minor image ofthe base 600 shown in FIGS. 6A-6C, such that the concave edge is shapedsuch that the fleshy part of the right palm located near the thumb fitsagainst the concave edge. In some variations, the same base may be usedfor both hands by moving the thumb rest (e.g., in a variation havingVelcro™ attachments, by having two locations on the base with Velcro™ towhich the thumb rest can be attached). In one of these variations, thethumb rest can be placed in a first position along concave edge 614 andnear straight edge 606 for use with the left hand, or in a secondposition along concave edge 614 and near straight edge 612 for use withthe right hand. In this variation, the base 600 may, but need not be,made symmetrical such that the lengths of straight edges 606 and 612 areequal, and/or edge 608 is convex with the same length and curvature asconvex edge 610. In another variation, the same base may be used forboth hands by moving the thumb rest from top flat surface 602 to bottomflat surface 604. In this variation, the curvature of the cornersbetween the top flat surface 602 and the edges and between the bottomflat surface 604 and the edges may be made equal, but need not be. Inother variations, the same base may be used for both hands by having twothumb rests attached at different positions.

It should be appreciated that the device may comprise other elements inaddition to the ones described here. For example, in some variations,the base 600 may have a strap to help the user hold the base in his orher hand. FIG. 7 illustrates an exemplary strap 700 attached to the base600 of FIGS. 6A-6C. The user can place his or hand through the strap 700to help secure the device in the hand while using the device. In theexample of FIG. 7, strap 700 may extend around the bottom flat surface604 of base 600. End 702 of strap 700 may be attached to straight side608, and end 704 of strap 700 may be attached to straight side 606. Ends702 and 704 may be attached to straight sides 608 and 606, respectively,by looping around pins 706 located within indentations 708 in base 600.It should be appreciated that the strap 700 may be attached at differentlocations on base 600. For example, although in FIG. 7 strap 700 isshown attached to side 608 at the end of edge 608 near edge 610, inother variations, strap 700 may be attached to side 608 closer to side612, such that when the device is held in the hand, strap 700 is at amore proximal location on the back of the hand. In other variations,strap 700 may be attached at one or both ends to bottom flat surface 604and/or top flat surface 602. In some variations, the strap may beadjustable or interchangeable to accommodate different hand sizes. Forexample, the strap may be made of a hook-and-loop fastener, such asVelcro™, that can be looped around pin 706 and adjustably attached toitself. As another example, the strap may be made out of an elasticmaterial, such as an elastic fabric or rubber, that can stretch aroundthe hand of the user. In yet other variations, the base 600 may haveother elements to help secure the device in the hand. For example, aglove may be attached to the bottom flat surface 604 of base 600, andthe user may place his or her hand in the glove when using the device.In variations in which the thumb rest is moveable such that the devicecan be used by the left and right hands, the strap, glove, or any otheradditional element may also be moveable to accommodate use by bothhands.

As another example, the device may comprise elements to increase itsportability. For example, the device may comprise a rubber band or otherelastic strap that can be used to hold the thumb rest toward the basewhen the device is not in use. In variations in which the thumb rest isremovable (e.g., in variations in which it is attached to the base withVelcro™), a rubber band or other elastic strap can be used to hold thetop and bottom members of the thumb rest together when it is detachedfrom the base. As another example, the device may be placed in a smallbag or pouch for ease of transport.

FIG. 8 illustrates an exemplary method of operating the device of FIGS.1-7. In operation as illustrated in FIG. 8, the device may be used byholding it in the left or right hand such that the fleshy part of thepalm near the thumb is against the concave edge of the base (805). Invariations having one or more elements to help the user hold the base inhis or her hand, the element(s) may be attached to the hand (e.g., astrap can be placed around the back of the hand, the hand can be placedin a glove). The user may then place his or her thumb on or in the thumbrest (810). The thenar muscles may be exercised by pushing down on thethumb rest so that the thumb moves toward the pinky finger (815). Thismotion of the thumb may compress the elastic member, causing it to applya resistive force to the thumb (820). After the thumb rest is pressed,it may be released (825), allowing the elastic member to return to itsresting state position, which may push the thumb rest away from the baseto its original position (830). This motion of the thumb may berepeated. The device may also be adjusted, such as to change the hand inwhich it is used, to change the length of the thumb rest, or to changethe stiffness of the elastic member.

Although the foregoing has, for the purposes of clarity andunderstanding, been described in some detail by way of illustration andexample, it will be apparent that certain changes and modifications thatwill become apparent to those skilled in the art may be practiced, andare intended to fall within the scope of the appended claims.Additionally, it should be appreciated that the devices described heremay comprise any combination of device components and features describedabove.

We claim:
 1. A device for strengthening thenar muscles of a hand,comprising: a base, wherein the base is shaped to fit in the hand; athumb rest attached to the base; and an elastic member comprising afirst end and a second end, wherein the first end is attached to thebase and the second end is attached to the thumb rest, and wherein theelastic member is configured to deform when the thumb rest is pressed.2. The device of claim 1, wherein the thumb rest comprises a hinge. 3.The device of claim 1, wherein the thumb rest comprises a retentionmember configured to keep a thumb of the hand in place while the thumbrest is pressed.
 4. The device of claim 1, wherein the elastic membercomprises a compression spring.
 5. The device of claim 1, wherein theelastic member comprises a piston.
 6. The device of claim 1, wherein theelastic member comprises an extension spring.
 7. The device of claim 1,wherein the first end of the elastic member is indirectly attached tothe base.
 8. The device of claim 1, wherein the base comprises a concaveside configured to fit against the fleshy part of a palm of the handnear a thumb of the hand.
 9. The device of claim 1, wherein the basecomprises a surface, and wherein the surface is texturized.
 10. Thedevice of claim 1, wherein the base comprises a strap that fits aroundthe hand.
 11. The device of claim 1, wherein the device is configured tostrengthen the thenar muscles of both a left hand and a right hand. 12.A handheld device for exercising thenar muscles of a hand, comprising: afirst rigid object; a second rigid object; a hinge directly orindirectly connecting the first rigid object and the second rigidobject, wherein the hinge is configured to cause the first rigid objectto pivot relative to the second rigid object; and an elastic member,wherein the elastic member is attached to both the first and the secondrigid objects, and wherein the elastic member is configured to resistthe pivoting of the first rigid object toward the second rigid object.13. The device of claim 12, wherein the first rigid object is configuredto be pivoted toward the second rigid object by pressing a thumb of thehand against the first rigid object and towards a palm of the hand. 14.The device of claim 13, wherein the device is configured to activate thethenar muscles when the first rigid object is pressed by the thumbtowards the palm.
 15. The device of claim 12, further comprising a baseconfigured to be held in the hand, wherein the hinge directly connectsthe first rigid object and the second rigid object, and wherein thesecond rigid object is attached to the base.
 16. The device of claim 12,wherein the elastic member comprises a compression spring.
 17. Thedevice of claim 12, wherein the elastic member comprises an extensionspring.
 18. The device of claim 12, wherein the elastic member isdetachable from the device.
 19. The device of claim 12, wherein theelastic member is interchangeable.
 20. A method for strengthening thenarmuscles of a hand using a handheld device, wherein the handheld devicecomprises a base, a thumb rest attached to the base, and an elasticmember having a first end and a second end, wherein the first end isattached to the base and the second end is attached to the thumb rest,the method comprising: pressing the thumb rest toward the base to deformthe elastic member using a thumb of the hand, wherein pressing the thumbrest causes the thenar muscles of the hand to contract.